column width calculation ignores 1 wide spanning cells.

The automatically calculated maximum width for a column skips looks like it skips spanning cells altogether. But it seems handy to use 1 wide spanning cells to adjust alignment. I'm using 1 wide spanning cells to center some column headings.

What do you think about including 1 wide spanning cells in the width calculation?

```ts
if (isSpanningCell(rowIndex, cellIndex)) {
return;
}
columnWidths[cellIndex] = Math.max(columnWidths[cellIndex], calculateMaximumCellWidth(cell));
```
([src line](https://github.com/gajus/table/blob/ecf73fa31eda3b1fe29abe1422ad3b3d8347f7d1/src/calculateMaximumColumnWidths.ts#L34))